Water in slow moving streams and in lakes, especially lakes produced by artifial dams, usually varies in temperature from cold at the bottom to relatively warm at the surface of the body of water with the water appearing to arrange itself into thermal stratas or layers. Experienced fishermen have long observed that particular types of fish tend to school and feed at particular temperature thermal levels in such bodies of water and it has also been observed that a school of fish that will show pronounced activity and strike at almost any moving object passing through the temperature stratum in which they are most active will abandon the chase of bait or lure that sinks into water colder than their preferred habitat stratum or that rises above the thermal stratum in which the particular species of fish are particularly active. Therefore, fishermen have traditionally attempted to design and select lures that were heavy and that could be employed for trolling at great depth or near the bottom of a body of water or alternatively to select lures of varying buoyancy so that they would troll somewhat under the surface or at the surface of said body of water. If the lure was very heavy it tended to sink not only to the desired level but eventually even beyond the desired strata. A buoyant lure intended for fishing at intermediate depths will usually tend to float upward with the passage of time and as the lure is pulled through the water with the result that the lure will soon rise above the temperature strata where fish of the desired species could be expected to strike. It is therefore a primary object of this invention to devise and disclose an artificial fishing lure having a temperature sensing capacity and thermostatically controlled depth selection and guidance means adapted to cause said lure to seek and to hold at a predetermined thermal stratum where fish of the desired species might be expected to be found.